Beetling mill with closed casing



Feb. 17, 1931. KRAMER 1,793,096

BEETLING MILL WITH CI |O$EID CASING Filed Jan. 5, 1929 Figl j i.

Patented Feb. 17, 1931 UNITED sir-Ares raranr oFr cE ERWIN KRAMER, OF BERLIN, GERIMANY, A SSIGNOR T0 HARTSTOFF-METALL-AKTIEN- GESELLSCHAFT, OF BERLIN-KOPENICK, G-ERJHANY I BEETLING- MILL WITH CLOSED CASING Application filed January 5, 1929, Serial 'No.

My invention relates to a beetling millof the closed-casing type which is improved in various respects with the objects to increase its efiiciency, as well as (and considerably) the degree of fineness of the material ground,

and to render it even possible to grind also tough and particularly hard metals to a remarkable degree of fineness.

The usual beetling mills having a casing,

. the walls of which are partly formed of for the coarser particles so that the disintegrating action exerted upon said latter particles, irrespective of whether this action is effected by the beetling members of the. mill, or by said particles impinging upon the wall of the same, or upon one another, is weakened. Still another phenomenon preventing a finer disintegration makes its appearance, viz; after a certain degree of fineness depending upon the kind of the material just being ground, its specific weight, the shape of the particles formed by the grinding, the construction'and the rotary speed of themill, the beats of the beetling'members upon the material just being ground become weaker and weaker which is due to the reason that the particles more and more circulate along the wall of the mill. The disintegration taking place after that stage has been reached is very slight, and is due chiefly to the friction of the particles at said wall and to their mutual friction when contacting with one an mill is due to a considerable diminishment, if

not complete elimination of, the above-mentionedcauses. The first characteristic fea ture of-the inventionis this, that the particles of the material just being ground are caused to leave fora certain time the pathof the 330,663, and in Germany January 14, 1928.

on by them; after that time has elapsed the particles return to and into their former path in order to be subjected anew to the action of the beetlingmembers. Thus an accumulation of particles in the path of the beetling memhers is prevented and the cushion action of the smaller particles considerably reduced. Furthermore, because of the ibmoval of the particles from the path of the beetling members, the circular movement of the particles in the casing, is considerably reduced.

- T he means for attaining these effects can be of difi erent kind. In the first place, the

. shape of the mill casing is important. WVhen a beetling member impinges upon a particle of the material just being ground, this particle smashed, and the minute fragments tend to fly away from one another in different directions if there is nothing in the way.

-llow, according to this invention, the mill.

casing is so shaped that the particles can be deviated laterally away fromthe circular path of the beetling members, but as it is necessary that they later on return into that path in order to be still furtherdisintegrated, means provided whereby they conducted back into the said circular path. Various means can be provided for this purpose; a particularly simple one consists in constrictin the lower art of the casing so that, although there is in the upper part of the same sufiicient room to allow of the particles escapi'ng'the beetling members, no such room is in the constricted lower part of the mill casing, the particles being there fore, subjected to the action of the beetling members in this part.

Another means for guiding the particles out of the path of the beetling members consists in the provision'of separate members, for instance guide surfaces; or if the particles are suificiently fine, currents of air or of a suitable gas maybe used as means for the purpose in view.

Enclosing the beetling paths in a casing in which a free space for the purpose stated is provided makes it, furthermore, possible to use, with very great success, a current of air for withdrawing the finished product from 'beethngmembers after they have been acted the mill, and it, besides, enables the particles 'mill, and removing or Withdrawing the product, can be effected, however, also continuously, in that one of the branches 10 and 11 is used for the uninterrupted introduction of the material to be ground, as Well as of the air, Whereas the other branch is used for Withdrawing the mixture of air and pulverulent material. a

The particles flying about in the chambers 8 and 9, as Well as those present between the beetling members, fill up comparatively large spaces, but their number, in relation to the unit of space, is comparatively small, and

it is, therefore, possible to render the effect of the air current particularly great. This is warranted also by the feature that, due to the particular arrangement of the apertures in the bulged-out portions or chambers of the mill casing, the speed of the air streaming into, and out of, said portions or chambers changes gradually. On the other hand, obstructions of the branches 10 and 11 located on the top of the mill are completely prevented. Finer particles are diverted 0E the path of the beetling members, as has already been stated.

I claim:

1. A beetling mill, comprising in combination a closed casing and beetling members adapted to revolve therein, said casing having on either side of said beetling members a chamber for the particles of the material struck by said beetling members to be diverted thereto out of the path of said beetling members converging Walls in said chamber causing the particles to return into the path of said beetling members, and means provided in the top of said casing for diverting the particles to said chambers.

2. A beetling mill as specified in claim 1, in Which said means consists of a part having oblique faces disposed at an angle to the plane of revolution of said beetling members.

In testimony whereof I afiiX my signature.

ERWI N KRAMER. 

